A wireless device (e.g., a cellular phone or a smartphone) in a wireless communication system may transmit and receive data for two-way communication. The wireless device may include a transmitter for data transmission and a receiver for data reception. For data transmission, the transmitter may modulate a radio frequency (RF) carrier signal with data to generate a modulated RF signal, amplify the modulated RF signal to generate a transmit RF signal having the proper output power level, and transmit the transmit RF signal via an antenna to another device such as, for example, a base station. For data reception, the receiver may obtain a received RF signal via the antenna and may amplify and process the received RF signal to recover data sent by the other device.
The wireless device may include one or more amplifiers to process analog signals. For example, some amplifiers may provide a processing gain (e.g., voltage and/or current gain) for relatively low amplitude signals, isolation for relatively sensitive signals, increased current for driving signals into transmission lines, and signal amplification for transmitting signals through a communication medium.
Some amplifiers may be exposed to environments that allow relatively high voltages to be undesirably coupled to one or more terminals of the amplifier. For example, an electrostatic discharge (ESD) event may expose relatively high voltages to the amplifier. If not protected, the amplifier may be damaged by the relatively high voltages. For example, a high voltage may cause a PN junction failure or an oxide failure and thereby damage one or more transistors included in the amplifier. Also, as device geometries (e.g., feature size) of the devices within the amplifier shrink, the devices within the amplifier become susceptible to damage with lower voltages. For example, a rapture voltage (e.g., voltage needed to damage a PN junction) associated with a metal oxide semiconductor (MOS) transistor may decrease as feature sizes decrease.
Thus, there is a need to improve ESD protection for amplifiers.